Devices for electrical connection of a power lead to an electrode, in particular a medical skin electrode, are disclosed in DE 37 19 474 A1. These connecting devices are used, for example, to measure physiological signals from living things, for example cardiac action voltages (electrocardiogram, EKG). For this purpose, electrodes are applied, for example, glued to the skin, and are connected to an electrical power lead via which the physiological signals in electrical form are routed to an evaluation unit. The device operates as a snap fastener and is snapped onto the contact stud of the electrode. The contact stud can be a separate part of an electrode of the conventional type or can, for example, with the bottom of a plate-shaped foot part, form the electrode surface itself.
Recently, a second type of electrode has been used, specifically so-called gel or film electrodes. These electrodes include a piece of metal foil or a piece of plastic film having an electrically conductive layer and coated with an electrically conductive gel. The detachable connection of one such electrode to a power lead in the form of a connecting cable can take place, or example, with an electrical clamp having two clamp jaws. At least one of the clamp jaws can swivel around the axis. The clamp jaws hold the essentially flat electrode, with which contact is to be made, between them by clamping. Similar clamps are known in other areas of engineering as xe2x80x9calligator clipsxe2x80x9d.
DE 198 01 173 C1 discloses a device which can make electrical contact with a first contact element and electrodes having a contact stud, and can make contact with a second contact element with film electrodes. This device is characterized in that the clamp jaws of the second contact element can be actuated to open by means of an actuating slide extending transversely to the lengthwise direction of the clamp jaws. The first contact element is provided simply as an option, and has a through opening which is invariable in its clearance for the contact stud. The invariable clearance for the contact requires high actuating forces, and for some applications, does not satisfy the required contact reliability.
Objects of the present invention are to provide a generic device which overcomes the disadvantages of the prior art.
In particular, with the device, if necessary, both electrodes can make reliable contact with one terminal stud and film electrodes on a permanent basis, simultaneously and repeatedly. In one special embodiment of the present invention, the device is operable in an ergonomically favorable manner, is to have a compact construction, and is to be economical to manufacture.
These objects are obtained by a device for electrical connection of a power lead to an electrode, comprising a first contact element for receiving the contact stud of a first electrode. The first contact element has a first spring element for biasing a contact zone of the first contact element into contact stud with the first electrode. Also, the device has a second contact element having first and second clamping jaws for engaging a second electrode. The second contact element can be actuated to open by an actuating element which can be pivoted around the first axis, against the action of an energy storage, to an open position.
At the same time or alternatively, preferably electrodes of a first type or a second type make contact with the first and second contact elements, respectively. In particular, the first electrode can make contact with the first contact element. This electrode has a plug element, for example a contact stud.
In particular, film electrodes can make contact with the second contact element. The film electrode has a terminal lug which is flat.
The first contact element is preferably essentially flat. The opening actuation of the first contact element takes place preferably by deflecting or shifting the contact zones essentially parallel to the surface formed by the first contact element.
Of the two clamp jaws of the second contact element, the first clamp jaw can swivel or pivot, preferably around an axle fixed in the housing of the device. The second clamp jaw is formed in one piece, preferably as part of the base element of the housing. The opening actuation of the second contact element takes place by rotation or pivoting of the actuating element, preferably by an angle of less than 90xc2x0, for example roughly 45xc2x0. The rotation of the actuating element takes place against the action or bias of the first energy-storing or spring element of the first contact element and/or against the action of a second energy-storing or spring element of the second contact element. Alternatively or additionally, the actuation can take place against the action of a third energy-storing or spring element located between the actuating element and the housing element of the device.
In one special embodiment of the invention, when the rotary actuating element is actuated, the contact zone of the first contact element can be actuated to open. In particular, upon rotation, the first energy-storing or spring element deflects for energy storage. By the opening actuation of the contact zone of the first contact element, the contact stud can be inserted into the device almost without exerting any force. Upon subsequent resetting of the actuating element, the contact zone is brought into electrical contact with the contact stud of the electrode by the stored energy. Moreover, this contact-making of the first contact element mechanically saves the contact zones, and thus, ensures permanently reliable contact-making.
Preferably, the first contact element has two contact zones symmetrical relative to the insertion axis of the device onto the contact stud and essentially flat. Furthermore, the contact zones are preferably located on contact tongues, each being integral with a spring arm on its edge side facing the insertion opening for the contact stud and being movable in the radial direction relative to the insertion axis of the device for the contact stud into contact with the latter. The spring legs can be strip-shaped, can form the first energy-storing element, and are preferably angled relative to the surface of the contact tongues, especially bent at a right angle.
In one special embodiment of the present invention, the actuating element has a first actuator by which the first energy-storing element can be deflected when the actuating element turns. For example, the first actuator can be made as an actuating pin located eccentrically relative to the first axis on the actuating element that deflects the spring leg upon contact while turning.
In one special embodiment of the present invention, the actuation element has an axle journal pivotally supported in the guide element of the housing of the device. At least one section of the axle journal can have an eccentrically extending area on its outside peripheral surface. Upon rotation around the first axis, deflection of the first energy-storing element occurs in the radial direction relative to the first axis based on the contact between the first energy-storing element and the eccentrically extending area of the outside peripheral surface. The forces for actuating or deflecting the first energy-storing element are thus low and can be set, and, in particular, further reduced by the corresponding length of the lever of the actuating element.
In one special embodiment of the present invention, the actuating element has a second actuator. When the actuating element is rotated around the first axis, the first clamp jaw of the second contact element can be pivoted around a second axis against the action of an energy storage by the second actuator to actuate the second contact element to an open position. The energy storage exerts a reset force on the clamp jaws of the second contact element, and can fundamentally be formed by the first energy-storing element of the first contact element. Preferably, however, the resetting action is provided by a second energy-storing element formed by the second contact element, by directly engaging the second contact element, and/or by a third energy-storing element acting directly on the actuating element.
Preferably, the first axis of rotation for the actuating element and the second axis as the axis of rotation for the second contact element are oriented at a right angle. Furthermore, the second actuator includes a crank guide with a crank path having a radial component relative to the first axis. The length and/or the course of this crank path allows adjustment of the opening angle of the clamp jaws relative to the angle of rotation of the actuating element or adaptation to special applications. If the second actuator has a crank path and the first clamp jaw has a guide pin which fits into the crank path, simply replacing the actuator adapts the opening angle of the clamp jaws to the respective application chosen depending on the angle of rotation of the actuating element.
In one special embodiment of the present invention, the second contact element has a second energy-storing element for providing spring-loaded contact-making of one contact zone of the second contact element with the electrode with which contact is to be made. Preferably, the contact zones of the second contact element are formed unitarily in one piece as two legs which can be elastically deflected. Execution as a punched/bent part of a sheet metal is especially favorable with respect to production costs and contact reliability. Each of the two preferably flat legs is fixed on one of the two clamp jaws, respectively. The U-shaped connecting section connects the two legs to be elastically deflected and can at the same time form a stop for the insertion of the electrode with which contact is to be made into the clamp mouth formed by the clamp jaws.
In one special embodiment of the present invention, the first and second contact elements are made in one piece. In any case, the two contact elements are connected to one another in an electrically conductive manner. The connection can be made for example by welding, especially spot welding, soldering, especially brazing, cementing, riveting, screwing or the like. The two contact elements are arranged in succession in the housing of the device such that they can be used alternately or simultaneously for making contact.
In one special embodiment of the present invention, the first and second contact elements are inserted into the base element of the housing and fixed by the housing guide element inserted in and interlocked into the base element. The contact elements are then covered and secured against unintentional contact. The base element, by preference, forms the second clamp jaw of the second contact element in one piece. The shockproof arrangement of contact zones or other electrically conductive areas of the contact elements occurs, in particular in all openings of the housing of the device. If necessary the maximum opening of the openings and the clamp jaws are selected such that the electrically conductive parts of the device cannot be touched by human extremities.
Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.